The present invention relates generally to electrical circuits and, more particularly, to analog-to-digital converters.
A successive approximation analog-to-digital converter (ADC) is commonly employed for applications that require low-power consumption and/or high resolution but that do not require high sampling rates. However, some applications may also require high-speed threshold detection in addition to the slower analog-to-digital (A/D) conversion of the successive approximation ADC.
For these applications, the high-speed threshold detection is performed by hardware that is separate from the successive approximation ADC, which results in duplicated functionality and may result in calibration inconsistencies between the hardware performing the high-speed threshold detection and the hardware performing the successive approximation ADC. Consequently, valuable circuit space is consumed and calibration issues may arise for the hardware employed for these applications. As a result, there is a need for improved techniques for providing threshold detection and A/D conversion.
Systems and methods are disclosed herein to provide A/D conversion and threshold detection. For example, in accordance with an embodiment of the present invention, a circuit is disclosed that provides successive approximation A/D conversion and high-speed threshold detection (e.g., comparison) operations by utilizing common hardware resources. Consequently, the circuit may require less circuit space than a conventional circuit having a successive approximation ADC and a separate threshold detector. Furthermore, the circuit may maintain a more consistent calibration (e.g., calibration registration) between the successive approximation ADC and threshold detection operations than the conventional circuit.
More specifically, in accordance with one embodiment of the present invention, a circuit includes a comparator adapted to receive a first and a second input signal and provide a comparator output signal; a first register adapted to store at least one threshold value and at least one successive approximation register value; a digital-to-analog converter adapted to provide the second input signal to the comparator, where the second input signal is based on one of the threshold values or one of the successive approximation register values from the first register; and a second register adapted to store the comparator output signal from the comparator, wherein the circuit is adapted to provide threshold detection or successive approximation analog-to-digital conversion of the first input signal.
In accordance with another embodiment of the present invention, a circuit includes a comparator adapted to receive a first and a second input signal and provide a comparator output signal; means for providing the first input signal to the comparator; and means for storing and selecting one from a number of threshold values and one or more successive approximation register values to generate the second input signal to the comparator.
In accordance with another embodiment of the present invention, a method of providing analog-to-digital conversion and threshold detection includes providing a first input signal; selecting a threshold value or a successive approximation register value to convert and provide as a second input signal; comparing the first input signal to the second input signal to provide a comparator output signal; providing the comparator output signal as a threshold detector result if one of the threshold values was selected; and providing the comparator output signal as a comparison result for successive approximation analog-to-digital conversion if the successive approximation register value was selected.
The scope of the invention is defined by the claims, which are incorporated into this section by reference. A more complete understanding of embodiments of the present invention will be afforded to those skilled in the art, as well as a realization of additional advantages thereof, by a consideration of the following detailed description of one or more embodiments. Reference will be made to the appended sheets of drawings that will first be described briefly.